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T Oka

Publications and source records attributed to T Oka.

At least 343 records · Page 19Linked to original sources
PubMed1997

Effect of troglitazone on blood insulin levels after pancreas transplantation with systemic venous drainage in rats.

BACKGROUND: Troglitazone is a new oral antidiabetic agent and has been reported to reduce insulin resistance and improve peripheral hyperinsulinemia in patients with noninsulin-dependent diabetes mellitus. To examine the effect of troglitazone on insulin regulation after pancreas transplantation with systemic venous drainage, we measured peripheral glucose and insulin levels and performed an intravenous glucose tolerance test. METHODS: We divided the rats into four groups: diabetic rats with a pancreas graft and administration of troglitazone at 40 mg/day orally (group P+T, n=4), rats with a pancreas graft only (group P, n=4), age-matched normal rats (group N, n=5), and diabetic rats (group DM, n=4). RESULTS: Fasting insulin levels in group P were relatively higher than those in group N, whereas the values in group P+T were normalized. In the intravenous glucose tolerance test, troglitazone clearly regulates sigma immunoreactive insulin levels of pancreas transplanted rats (P vs. P+T: 244+/-23 vs. 145+/-14 microU/ml, P<0.05). CONCLUSION: Hyperinsulinemia induced by systemic venous drainage, which may progress atherosclerosis, can be controlled with troglitazone treatment.

Animals↗
PubMed1997

The stiffness of lymph nodes containing lung carcinoma metastases: a new diagnostic parameter measured by a tactile sensor.

BACKGROUND: It is believed that the stiffness or hardness of a lymph node containing a metastasis differs from that of lymph node without a metastasis because of the difference in tissue density, which is derived from the lymph node's histopathologic features. Prior to this study, however, there had been no attempts to quantify the hardness or stiffness of lymph nodes. The authors developed a new tactile sensor and system for measuring the stiffness (g/cm) of lymph nodes accurately, and they studied its utility as a tool for diagnosing lymph node metastases. METHODS: Clinical specimens were obtained from 14 patients who underwent lobectomy or pneumonectomy with hilar and mediastinal lymph node dissection for nonsmall cell lung carcinoma at the University of Tokyo between January and July 1996. With the tactile sensor developed by the authors, 212 resected lymph nodes were measured for their stiffness. RESULTS: Among these 212 resected lymph nodes, 57 were diagnosed as containing metastases (38 from adenocarcinomas and 19 from squamous cell carcinomas). The mean stiffness of the lymph nodes that contained metastases was 3.35 +/- 1.57 g/cm, and that of lymph nodes without metastases was 1.23 +/- 0.50 g/cm (P < 0.001). Receiver operating characteristic analysis revealed that the area under the curve was 0.93, indicating excellent accuracy of the method. When the cutoff was 1.5 g/cm, the sensitivity was 91.2% and the specificity was 78.1% for detection of lymph node metastases. CONCLUSIONS: Measurement of the stiffness of resected lymph nodes was confirmed as an accurate approach to diagnosing lymph node metastases without knowledge of other factors, such as lymph node size or color.

Aged↗
PubMed1997

Biphasic modulation in the trigeminal nociceptive neuronal responses by the intracerebroventricular prostaglandin E2 may be mediated through different EP receptors subtypes in rats.

To determine which prostaglandin E2 (PGE2) receptor subtypes are involved in the brain-derived PGE2-induced changes in nociception, we injected synthetic EP1, EP2 and EP3 receptor agonists (0.01 fmol to 10 nmol) into the lateral cerebroventricle (LCV) of urethane-anesthetized rats and observed the changes in the responses of the wide dynamic range (WDR) neurons in the trigeminal nucleus caudalis to noxious pinching of facial skin. The enhancement and suppression of the nociceptive responses of the WDR neurons were observed after the LCV injection of MB28767 (an EP3 receptor agonist) at a low dose range (1-100 fmol) and 17-phenyl-omega-trinor PGE2 (an EP1 receptor agonist) at high doses (1-10 nmol), respectively. Furthermore, the suppression of nociceptive neuronal responses after the LCV injection of PGE2 (1 nmol) was completely blocked by SC19220 (an EP1 receptor antagonist, 300 nmol). On the other hand, butaprost (an EP2 receptor agonist) at any doses tested (0.1 fmol to 1 nmol) had no effect on the nociceptive responses. The LCV injection of MB28767 (10 fmol) and 17-phenyl-omega-trinor PGE2 (1 nmol), which respectively enhanced and suppressed the nociceptive neuronal responses, did not affect the responses of the low threshold mechanoreceptive neurons to innocuous tactile stimuli. These results provide electrophysiological evidence that brain-derived PGE2 induces mechanical hyperalgesia and hypoalgesia through EP3 and EP1 receptors, respectively, in the rat.

Analgesics↗
PubMed1997

The last phase of the reprotonation switch in bacteriorhodopsin: the transition between the M-type and the N-type protein conformation depends on hydration.

In order to elucidate the mechanism of the reprotonation switch of bacteriorhodopsin, the protein conformation of the M intermediate of the D96N mutant was examined at various hydration conditions by X-ray diffraction and FTIR spectroscopy. We observed two distinct protein conformations at different levels of hydration. One is like in the N photointermediate, although in this case with an unprotonated Schiff base. It is stabilized in highly hydrated samples. The other is a protein conformation identical to that in the normal M intermediate of wild-type bacteriorhodopsin, which is stabilized in partially dehydrated samples. The hydration dependence of the structural transition between the M-type and the N-type conformations suggests that there is a change in the binding of water at the cytoplasmic surface. Thus, more water molecules bind in the N-type structure than in the M-type. This is consistent with the idea that the conformational change from the M-type to the N-type corresponds to the opening of the proton channel to the cytoplasmic surface by tilt of the cytoplasmic end of helix F, and that this is required for proton transfer from Asp-96 to the retinal Schiff base.

Asparagine↗
PubMed1997

Fibroblast growth factor-2 expression is up-regulated after denervation in rat lung tissue.

To understand the role of fibroblast growth factor-2 (FGF-2) during the denervation-reinnervation processes which occur after lung transplantation, we studied FGF-2 gene expression in a rat lung denervation model. The temporal profile of FGF-2 mRNA in denervated rat lungs was quantitatively assessed by competitive reverse transcription polymerase chain reaction (RT-PCR) method. The level of FGF-2 mRNA was consistently higher in denervated lungs, showing a peak value on the 5th post-operative day. Immunohistochemical analysis with an anti-FGF-2 monoclonal antibody disclosed immunoreactivity in Schwann cells at the distal severed end of the nerve fascicle located at the lung hilus, 1 week post-surgery. This study indicates that FGF-2 gene expression is up-regulated following denervation and suggests possible roles of FGF-2 in the reinnervation process of lung tissue.

Animals↗
PubMed1997

Three vha genes encode proteolipids of Caenorhabditis elegans vacuolar-type ATPase. Gene structures and preferential expression in an H-shaped excretory cell and rectal cells.

The proteolipids of the vacuolar-type H+-ATPase (V-ATPase) are major components of the integral membrane sector. The vha-1 and vha-2 (vacuolar-type H+-ATPase) genes in Caenorhabditis elegans encode putative 16-kDa proteolipids and are tandemly localized on chromosome III. The vha-2 gene has three exons, whereas vha-1 has no introns. The deduced amino acid sequences of the two genes exhibit about 60% identity with the homologues from yeast, mouse, and cow. The mRNAs of both vha genes are trans-spliced to spliced leaders, suggesting that these genes constitute a polycistronic transcriptional unit. The vha-4 gene consists of four exons and is very similar to the yeast VMA16 gene that codes for the 23-kDa proteolipid. This is the first example of three distinct V-ATPase proteolipids being identified in higher eukaryotes. Northern blot and transgenic analyses show that the three vha genes may be highly expressed in the H-shaped excretory cell, rectum, and a pair of cells posterior to the anus. These results suggest that the V-ATPase activity may be important for exporting toxic compounds or metabolic wastes in this organism.

Amino Acid Sequence↗
PubMed1997

Prostaglandin E2 may induce hyperthermia through EP1 receptor in the anterior wall of the third ventricle and neighboring preoptic regions.

We have previously reported that intracerebroventricular injection of prostaglandin E2 (PGE2) induces hyperthermia possibly through EP1 receptors in the rat. In the present study, to determine the sites in the brain where PGE2 induces hyperthermia through EP1 receptors, we microinjected an EP1 receptor agonist, 17-phenyl-omega-trinor PGE2 (17-Ph-PGE2, 100 ng) into different sites in the rat brain and observed the colonic temperature (Tco) for 2 h in a 23 +/- 1 degrees C environment. Responsive sites where 17-Ph-PGE2 (100 ng) produced a rise in the Tco of more than 1.1 degrees C within 60 min after injection were found in the medial preoptic area, the subchiasmatic portion of the median preoptic nucleus, the anterior wall of the third ventricle (A3V) and the ventral portion of the diagonal band of Broca. Among these sites, the A3V was the most responsive. In contrast, microinjection of neither butaprost (an EP2 agonist, 100 ng) nor M&B28767 (an EP3 agonist, 100 ng) into these four sites had any effect on the Tco. Intracerebroventricular pretreatment with SC-19220 (an EP1 antagonist, 100 microg) inhibited the rise in the Tco which was induced by microinjection of PGE2 (50 ng) into the A3V. These results thus suggest that PGE2 induces hyperthermia by stimulating EP1 receptors in the A3V and the neighboring preoptic region.

Alprostadil↗
PubMed1997

Butyrate activates the WAF1/Cip1 gene promoter through Sp1 sites in a p53-negative human colon cancer cell line.

Butyrate is a well known colonic luminal short chain fatty acid, which arrests cell growth and induces differentiation in various cell types. We examined the effect of butyrate on the expression of WAF1/Cip1, a potent inhibitor of cyclin-dependent kinases, and its relation to growth arrest in a p53-mutated human colon cancer cell line WiDr. Five millimolar butyrate completely inhibited the growth of WiDr and caused G1-phase arrest. WAF1/Cip1 mRNA was rapidly induced within 3 h by treatment with 5.0 mM butyrate, and drastic WAF1/Cip1 protein induction was detected. Using several mutant WAF1/Cip1 promoter fragments, we found that the butyrate-responsive elements are two Sp1 sites at -82 and -69 relative to the transcription start site. We also found that a TATA element at -46 and two overlapping consensus Sp1 sites at -60 and -55 are essential for the basal promoter activity of WAF1/Cip1. These findings suggest that butyrate arrests the growth of WiDr by activating the WAF1/Cip1 promoter through specific Sp1 sites in a p53-independent fashion.

Base Sequence↗
PubMed1997

Renal tubular abnormalities in hydrops fetalis: a histological and immunohistochemical study.

An immunohistochemical study of renal tubule cell differentiation in hydrops fetalis was performed using antibodies against lysozyme, CD15, keratin, epithelial membrane antigen and Leu-7, and formalin-fixed, paraffin-embedded sections of tissue that was obtained at autopsy. In 3 cases among 17 cases of hydrops fetalis (17.6%) there was a marked decrease in the number of cells stained positively for lysozyme, suggesting abnormal differentiation of the cells of the proximal convoluted tubules. This is the first report concerning the abnormalities of the renal tubular epithelium in hydrops fetalis.

CD57 Antigens↗
PubMed1997

Biphasic alteration in the trigeminal nociceptive neuronal responses after intracerebroventricular injection of prostaglandin E2 in rats.

To investigate the role of prostaglandin E2 (PGE2) in the brain in nociception electrophysiologically, we injected PGE2 (0.1 fmol(-1) nmol) into the lateral cerebroventricle (LCV) of anesthetized rats and observed the changes of the responses of the wide dynamic range (WDR) neurons in the trigeminal nucleus caudalis to noxious pinching of facial skin. The LCV injection of PGE2 at 1 fmol and 10 fmol enhanced the responses of the majority of WDR neurons to noxious stimuli, whereas that of PGE2 at 100 pmol and 1 nmol suppressed them. The enhancement and suppression of the nociceptive responses of WDR neurons were observed 15-25 min and 5-15 min after injection of PGE2 at 10 fmol (3.53 pg) and 1 nmol (353 ng), respectively. On the other hand, the LCV injection of PGE2 at both 10 fmol and 1 nmol had no effect on the responses of the low threshold mechanoreceptive neurons to skin brushing. These results provide electrophysiological evidence that brain-derived PGE2 has biphasic effects on nociception, i.e., it induces mechanical hyperalgesia at lower doses and hypoalgesia at higher doses in rats.

Activity Cycles↗
PubMed1997

Cloning and sequencing of cDNA encoding NG,NG-dimethylarginine dimethylaminohydrolase from rat kidney.

Three cDNA clones encoding NG,NG-dimethylarginine dimethylamino-hydrolase (EC 3.5.3.18) have been isolated from a rat kidney lambda gt11 library using a probe prepared by PCR on the basis of partially determined amino-acid sequences of the enzyme. The sequence analyses of the cDNAs established that the 3008 bp cDNA contains 855 bp open reading frame encoding 285 amino acids (M(r) 31414), 3'-flanking region (1722 bp) and 5'-flanking region (431 bp). The amino-acid sequences of all the peptides isolated from the purified enzyme were shown to be included in the deduced amino-acid sequence. Northern blotting analyses showed that the mRNA (4 kb) is ubiquitously expressed in various rat tissues.

Amidohydrolases↗
PubMed1997

Observation of Delta|k - l | = 3 Transitions in the nu3 Band of H3 O+

Although the vibration-rotation spectrum of H3 O+ has been studied extensively, there has been no experimental information on the value of the C rotational constant because of the absence of any observed Delta|k - l | not equal 0 forbidden transitions. However, as pointed out by Verhoeve et al. in their far-infrared spectroscopic work [P. Verhoeve, M. Versluis, J. J. Ter Meulen, W. L. Meerts, and A. Dynamus, Chem. Phys. Lett. 161, 195-201 (1989)], a near degeneracy exists between some (J , 0)+ and (J , 3)- ground state rotation-inversion levels, which causes sizable shifts in these levels due to off-diagonal centrifugal distortion. These shifts were observed in the ground state combination differences of the nu3 fundamental transitions. We have observed 11 forbidden Delta|k - l | = 3 transitions to the nu3 band induced by the mixing in the ground state and involving the J = 7, 9, and 11 levels, and determined the energy difference between different K levels, the C rotational constant, and the off-diagonal centrifugal distortion mixing coefficient.

Journal Article↗
PubMed1997

Hemoptysis from an emphysematous bulla developing after open-heart surgery: report of a case.

We present herein the case of a 62-year-old woman with an emphysematous bulla who developed intractable hemoptysis 16 days after undergoing mitral and aortic valve replacement with tricuspid annuloplasty. A bronchoscopic examination with balloon occlusion of the bronchial lumen revealed that the blood source was the right middle lobe bronchus. A computed tomographic (CT) scan of the chest subsequently demonstrated a blood-filled emphysematous bulla in the right middle lobe. A right middle lobectomy was performed and the bulla was observed to be swollen with clotted blood. The respiratory tract bleeding stopped immediately after the lobectomy. Pathohistological examinations suggested that disruption of the pulmonary vessels in the wall of the bulla had caused the respiratory tract bleeding.

Aortic Valve Insufficiency↗
PubMed1997

Laparotomy versus interventional radiological procedures for the implantation of arterial infusion devices.

Although there have been numerous reports on implantable infusion devices for chemotherapy of patients with malignancy, we occasionally face problems with this therapy due to trouble with implantation. We performed a retrospective review of 81 implantations in 77 patients, who were treated with intraarterial chemotherapy via implanted devices from 1985 to 1993. They were divided into two groups according to the procedures: the operative procedure group (group A, n = 41) and the interventional radiological procedure group (group B, n = 36). Both groups were then analyzed regarding the respective complications. We experienced 25 complications: (a) 9 obstructions of the catheter, (b) 4 infections, (c) 4 dislocations of the catheter, (d) 3 hematomas, (e) 3 breakdowns of the device, (f) 1 pneumothorax, and (g) 1 hepatic artery occlusion. The results of a comparison of the complication rate between groups A and B were (a) 14.0%:8%, (b) 4%:0%, (c) 0%:10%, (d) 4%:2%, (e) 7%:0%, (f) 0%:2%, and (g) 2%:0%, respectively. A statistically significant difference was observed for (b) and (c) (P < 0.05). Infection occurred mainly in the cirrhotic cases of group A, but not in group B. In addition, one case fell into fatal sepsis. Based on the above findings, the interventional radiological procedure is thus considered to be the appropriate method for the prevention of infection in the case of a compromised host.

Adult↗
PubMed1997

Disopyramide improves the balance between myocardial oxygen supply and demand in patients with hypertrophic obstructive cardiomyopathy.

We evaluated the effects of disopyramide in terms of the balance between myocardial oxygen supply and demand in patients with hypertrophic obstructive cardiomyopathy (HOCM). The myocardial oxygen supply was evaluated by measuring coronary flow velocity and the myocardial oxygen demand was assessed by the pressure-volume area (PVA). The time velocity integral of coronary flow did not change significantly (20 +/- 6 to 21 +/- 8 cm), but the peak left ventricular pressure and left ventricular external work decreased significantly (206 +/- 44 to 157 +/- 37 mmHg, P < 0.001; 1.09 +/- 0.33 to 0.80 +/- 0.23 J/beat, P < 0.001) after disopyramide administration. From theoretical analysis using these data, we concluded that disopyramide improves the myocardial oxygen supply-demand balance in patients with HOCM.

Adult↗
PubMed1997

Effects of chronic cigarette smoke inhalation on the development of senile lung in senescence-accelerated mouse.

The senescence-accelerated mouse (SAM) manifests most of the features of function and morphology in the senile lung with aging. However, little is known about the effects of age and cigarette smoke on alterations of the lung in SAM. In the present study, we examined the effects of chronic cigarette smoke inhalation and age on the function and morphology of lungs in two strains of SAM, SAMP2 (senescence-prone strain) and SAMR1 (senescence-resistant strain), from 6 months of age (young) and 18 months of age (aged). After 4 weeks of cigarette smoke inhalation, a small but significant airspace along with a leftward shift of the pressure-volume (P-V) curve was observed in young SAMP2, but not in SAMR1. However, the airspace size of young SAMP2 with cigarette inhalation was smaller than that in aged SAM with air inhalation, suggesting that the effect of age may be greater than that of the small burder of tobacco smoke on the lung alterations in SAMP2. In the aged SAM, there were no differences in function and structure between tobacco-exposed and air-exposed mice. Because the changes in the lungs of young SAMP2 exposed to cigarette smoke were partly simulated with age-related alterations in human lung, and because age-dependent changes of lungs were clearly investigated in SAMP2, this strain may be an interesting animal model for investigating the effects of age and/or cigarette smoke on alterations in lung structure and function.

Aging↗
PubMed1997

Histopathologic findings of advanced neuroblastoma after intensive induction chemotherapy.

BACKGROUND: Histopathologic findings of advanced neuroblastoma after intensive induction chemotherapy have not been studied well. METHODS: In the present study, all of the surgical specimens from 19 patients who had advanced abdominal neuroblastoma and were pretreated intensively with the protocol of the Study Group of Japan were reviewed. The authors found that dissection of the contralateral lymph nodes is mandatory in advanced neuroblastoma when the goal is the complete dissection of the abdominal disease. Effects of chemotherapy were graded histologically according to the ratio of viable residual neuroblastoma tissue to total areas of the tumor, including neuroblastoma, ganglioneuroblastoma, ganglioneuroma, hemorrhage, necrosis and fibrosis, in five ranks from ( ) to (-). CONCLUSIONS: The newly introduced, highly cytotoxic regimen of the Japanese protocol, designated "A3," appears to be more effective histologically than the conventional regimen, designated "A1" or "new A1." Effects designated ( ) or (++) were prerequisites for survival in stage IV disease, but some stage III patients with the (+) effect survived.

Abdominal Neoplasms↗